[iannrandall]

Are you letting the pre heat do it's job or just trying to start from cold. Pre heat is required below a certain temp which I think is about 5c. I've had a few diesel vehicles and if you don't use it you will get a cloud of smoke from a cold engine, also I have found you would get a lack of smoothness till the engine has run for a short period.
I will admit I hardly ever start without using this. Now the debate is am I right or wrong? But I have been driving diesels this way for many years.